This invention relates in general to an apparatus and method for inserting solder preforms on selected circuit board back plane pins.
Circuit boards utilized in electronic products often incorporate pins which pass perpendicularly through the circuit board in order to provide electrical connections to voltage and ground planes printed on the surfaces of the circuit board. In some environment, these pins are a part of a component or connector. In such case, the circuit board is drilled with a pattern of holes corresponding to the pattern of pins coming out of the component or connector and the component or connector is mounted on the circuit board with its pins passing through the corresponding holes in the circuit board. When it is desired to electrically connect a subset of these pins to the printed voltage and ground planes of the circuit board they pass through, preformed donut shaped pieces of solder are often utilized. After the component is mounted on one side of the circuit board, solder preforms are inserted on those pins extending perpendicularly through the other side of the circuit board to which an electrical connection between the pin and the voltage or ground plane is desired. The solder preforms are only inserted on those pins which require electrical connection to the circuit board's voltage or ground plane.
After the solder preforms have been inserted, the entire circuit board is put in an oven. The heat generated by the oven melts the solder preforms and the solder flows between the pins containing solder preforms and the corresponding hole in the circuit board, creating an electrical connection between the pins and the circuit board's printed ground or voltage plane.
In the prior art, various methods and apparatuses have been utilized to insert solder preforms on selected circuit board back plane pins. Originally, tweezers were utilized by an operator to position a solder preform on each selected pin. An advance over this method is the use of a gun which inserts a solder preform on a pin after an operator positions the tip of the gun over the pin. The gun may be used in conjunction with a pattern which indicates to the operator which pins are to have solder preforms inserted on them. The major disadvantages of these and other prior art methods and apparatuses is that they are time consuming, requiring an operator to perform many repeated insertion operations. In addition, the prior art methods may result in operator errors as the operator often fails to follow the instructions or pattern specifying which pins are to have solder preforms inserted on them. A further drawback of the insertion gun of the prior art is that the solder preforms, due to their flux coating, often stick to the inside of the gun's dispenser tube.
It is a general object of the present invention to eliminate these and other drawbacks of the prior art by providing an improved apparatus and method for inserting solder preforms on selected circuit board back plane pins.
It is a further object of the present invention to provide an apparatus and method which speeds up the process of inserting solder preforms on a selected subset of a circuit board's back plane pins.
It is another object of the present invention to provide an apparatus and method for inserting solder preforms on selected back plane pins that is particularly well adapted to inserting the same pattern of solder preforms on the back plane pins of a large number of circuit boards.
It is still another object of the present invention to provide an apparatus and method for inserting solder preforms on selected circuit board back plane pins which minimizes errors caused by an operator inserting a solder preform on a pin not requiring one or failing to insert a solder preform on a pin which does require one.
These and other objects, features and advantages of the present invention will become more apparent from the detailed description of the preferred embodiment when read in conjunction with the drawings.